Purpose – The purpose of this study is to explore if and how companies strive for a harmonization of management accounting systems in their international business units to support company-wide consistent strategy implementation and to analyze the underlying drivers and pitfalls. Our paper is motivated by the tension between the need for consistent strategy implementation in the different international business units of multinational companies and the traditional differences in management accounting practices across countries. Design/methodology/approach – The field study comprised semi-structured in-depth interviews with management accounting experts in selected German and Spanish business units of 15 major German multinational companies. Findings – The authors identified strong efforts for company-wide harmonization of management accounting practices and found that beside explicit initiatives set by corporate headquarters, more implicit pressures such as the education of management accountants, the work of global consultancies and the use of standardized ERP-systems constitute strong drivers of the identified harmonization. Practical implications – The findings highlight implicit pressures as important drivers of the harmonization of management accounting systems in the international business units of multinational companies. Taking these implicit pressures into consideration can help multinational companies striving for a harmonization of business unit management accounting for consistent strategy implementation. Originality/value – Building on a unique sample of pairs of German and Spanish business units of 15 major German companies, the field study explores harmonization practices and its drivers in multinational companies.